Our goal for the current year was to repeat the DMN and 3-methylcholanthrene carcinogenicity study. We, also, intended to repeat some of the enzyme determinations in chronic studies and to perform some in vitro mutagenesis assays. BIBLIOGRAPHIC REFERENCES: Friedman, M.A., V. Sanders, and S. Woods. Suppression of dimethylnitrosamine metabolism and toxicity by nitrososarcosine and other nitrosamines, Toxicol. Appl. Pharmacol. 36:395-401, 1976. Friedman, M.A. and V. Sanders. Effects of piperonyl butoxide on dimethylnitrosamine metabolism and toxicity in Swiss mice. Journ. Toxicol. and Env. Health 2:67-75, 1976.